Illuminated panel assembly



Feb. 12, 1963 J. N. DUPREE ILLUMINATED PANEL ASSEMBLY 2 Sheets-Sheet 1 Filed D90. 13, 1959 INVC/VTOL: .famef 1% 0140/26 I afixweya;

Feb. 12, 1963 J. N. DUPREE ILLUMINATED PANEL ASSEMBLY 2 Sheets-Sheet. 2

Filed Dec. 13, 1959' United States Patent tion of California Filed Dec. 15, 1959, Ser. No. 859,754 6 Claims. (Cl. 240-8.16)

This invention relates to means for illuminating panels of the type commonly used in aircraft. Such a panel is of laminar construction with a thick main layer of transparent plastic, a thin outer opaque layer and a thin translucent layer under the opaque layer. The opaque layer has indicia cut-outs which are illuminated by edge lighting, i.e., by light transmitted through the main transparent layer edgewise thereof from one or more lamps mounted in the plane of the main layer.

Many different kinds of lamp housings and methods of mounting lamp housings in a panel have been developed for this purpose with conductors incorporated in the panels for energizing the lamps and with provision for lamp replacement. in general, such panel assemblies have been of costly, complicated construction and, moreover, the lamp housings commonly take up space on the front faces of the panels and protrude conspicuously from the front faces. One need, therefore, is for a simpler and less expensive construction and another need is to conceal the lamp mounting means in the panel.

One answer that has been proposed for these two needs is to use miniature lamp bulbs that are small enough to be concealed within the thickness of the panel and which have a service life on the order of one hundred thousand hours. This service life is long enough for an airplane to become obsolete and completely worn out. The problem, however, is how to incorporate such a lamp in the'panel.

One proposal is simply to imbed the miniature lamps permanently in the panel itself, for example by permanently potting the lamps in recesses in the back face of the panel. This proposal is not commonly acceptable,

however, because there is always the possibility that one of the imbedded long-life lamps will fail with the necessity of replacing the whole panel assembly.

The invention solves this problem by providing a recess or blind bore in the panel extending inward from the back face of the panel, by permanently imbedding the miniature lamp in a body of light-transmitting material, and by mounting the light-transmitting body mechanically in the recess in a removable manner. This solution offers the same advantages in simplicity and economy as permanently imbedding the lamp in the panel material and also completely conceals the lamp mounting in the desired manner. If the lamp should fail, the body that imbeds the lamp may be removed and replaced with very little trouble, there being no necessity for replacing the whole panel assembly.

To carry out this concept, some provision must be made for connecting the lamp in the removable body to circuit conductors, for example printed circuit conductors on the panel. Such a provision should be carried out as nearly as possible within the thickness of the panel.

The present invention meets this requirement by using a bayonet and slot arrangement for removably mounting the lamp-carrying body in the back recess of the panel and by further providing the removable lamp-carrying body with a thin relatively rigid radial flange that overlaps the rim of the panel recess. Conductor means partially imbedded in the removable body are exposed on the inner face of the radial flange for connecting the lamp to circuit conductors on the back of the panel. The exposed elements of the conductor means are resilient elements that are flexed by the operation of mounting the body in the panel recess. This arrangement provides for pressure contact with the adjacent panel conductors.

Another problem to which the invention is directed is to avoid excessive voltage drop in a printed circuit. In a common construction, a pair of printed circuit conductors wind around the back face of the panel in a circuitous manner to avoid the various obstacles that are inevitably present. The lamps that are near the end of such a long circuitous pair of conductors may be relatively dim because of the large voltage drop over the relatively long conductors.

This situation can be remedied to a certain extent by bringing the pair of circuitous conductors back to the starting point so that the circuit consists of two continuous conductors. In many instances, however, it is not possible to bring the two conductors back to the connection point because the panel is too crowded in this region. Even when it is possible to bring the two circuitous conductors back to the connection point, the lamps that are furthest from the connector fitting may be noticeably dim.

The present invention solves this problem by an arrangement which permits the conductors on the two sides of the lamp circuit to cross at each of the lamps or at least at some of the lamps. Such an arrangement makes it possible to keep down the distance of current flow to avoid excessive voltage drop. Such an arrangement also makes it possible to employ a plurality of spaced connector fittings in parallel to keep all of the lamps bright.

A further feature of the invention is that the lamp-carrying bodies that are removably mounted in the recesses on the back face of the panel may also incorporate means for connecting the circuitry of a panel to an source. Thus a removable lamp-carrying body may be provided with connector elements for the purpose of plugging the panel into an source. A further feature of the invention in this regard is that recesses may be provided in the back of the panel for the sole purpose of connecting'the panel to an source, no lamp-carrying bodies being mounted in the recesses. The recesses are occupied by bodies that serve the sole purpose of providing the plug connecting elements.

A further feature of the invention is the provision of colored light-transmitting plastic around the imbedded lamps for the purpose of providing colored light. The lamp-carrying body may be made of colored transparent plastic for this purpose. Preferably a sleeve of colored transparent plastic is used. Such a light-filtering sleeve may be permanently mounted as a liner in a panel recess in which the lamp-carrying body is mounted or, if desired, the sleeve may be permanently bonded to the lamp-carrying body. The invention further contemplates the application of the same principles to the construction of indicator lamps for mounting in edge-lighted panels. Such an indicator lamp is visible from the front face of the panel and is controlled by a special circuit, for example a circuit responsive to the opening of a bay or responsive to extension and retraction of landing gear.

The features and advantages of the invention may be understood from the following detailed description considered with the accompanying drawings.

In the drawings, which are to be regarded as merely illustrative FIG. 1 is a bottom plan view of a panel constructed in accord with the invention;

FIG. 2 is a fragmentary section on an enlarged scale along the line 2-2 of FIG. 1 showing one of the recesses in the back of the panel;

FIG. 3 is a side elevation of a lamp-carrying body that is adapted for mounting in the panel recess in a removable manner;

FIG. 4 is a plan view of the lamp-carrying body as seen along the line 4-4 of FIG. 3;

FIG. 5 is an enlarged fragmentary sectional view taken along the line 55 of FIG. 4;

' 1G. 6 is an exploded perspective view of the components that enter into the construction of a lamp-carrying block;

FIG. 7 is a perspective view of a lamp-carrying block that is adapted to serve as a connector fitting for plugging the panel into an EMF. source;

FIG. 8 is a view of the same lamp-carrying body, the view being partly in side elevation and partly in section along the line 8-8 of FIG. 7;

FIG. 9 is a fragmentary plan view of the panel showing how the principles of the invention may be applied to theprovision of an indicator lamp, the lamp in this 7 instance indicating when a bay of the aircraft is open;

FIG. 10 is a fragmentary sectional view taken as indicated by the line HE -1t of FIG. 9 with the lamp-carrying plastic body spaced from the recess in the panel; and

FIG. ll is a view similar to FIG. 10 showing how the recess may extend all the way to the front face of the panel.

The panel that is generally designated by the letter P in FIGS. 1 and 2 is of a well-known laminar construction that includes a relatively thick main layer 10 of transparent plastic and a thin outer opaque layer 12 superimposed on an intervening translucent layer 14. The

translucent layer 14 may be white, for example. In a well-known manner, the opaque layer 1'2 has cut-outs in the form of letters, numerals, arrows or other indicia, which indicia are illuminated by light transmitted through the main layer ltl edgewise thereof. The inner face of the panel may include a white translucent layer 15 to refleet interior light.

The panel P is provided with conductors mounted rearwardly thereof for energizing the various illuminating lamps. A feature of the invention is the concept of employing a printed circuit arrangement on the back of the panel in which, in effect, the two legs of the circuit cross over or intersect at the location of each of the lamps. In FIG. 1, there are six recesses, each designated by the letter R, to receive lamp-carrying bodies and conductors of the two opposite legs of the lamp circuit cross over or intersect at each of these recesses.

' In the construction shown, two fittings, each designated by the letter F, are included in the panel assembly to v function in parallel for plugging the lamp circuit into an E.M.F.source. One leg of the lamp circuit that is energized by means of the fittings F comprises a lead 16 from each of the two fittings F and a series of conductors 18 that conform to two lines, eachof the lines intersecting three of the recesses R. The conductors do not actually cross the recesses but, as heretofore indicated, are bridged by conductor means'in the lamp-carrying bodies that are to be mounted in the recesses R. In like manner, the other leg of the lamp circuit includes leads 2th from the two fittings 'F and a series of conductors 22 that are per- .pendicular to the conductors 18 and conform to the pattern of three lines, each line intersecting tWo of the recesses.

. FIG. 2 shows a recess R to receive a lamp-carrying body and FIG. 3 shows such a lamp-carrying body 25 for mounting in the recess. The lamp-carrying body 25 is a cylindrical body of a suitable transparent or semi-transparent plastic and is formed with a pair of diametrically I opposite bayonet lugs 26 for cooperation with a corresponding pair of bayonet slots 23 in the recess R. In this instance, it is contemplated that the light from the lamp 31th in the body '25 will pass through a colored filter for illuminationof the panel by colored light. For this purpose, a sleeve 32 of colored transparent plastic, for example red plastic, may be permanently mounted as a liner in the recess R and may be considered as a unitary or light mask 34, which light mask may comprise a thin flanged sheet metal disk. The metal diskalso has the function of a thermal conductor to prevent excessive concentration of the heat from the lamp. The diametrically opposite bayonet slots 28 are on the inner circumference of the light-filtering sleeve 32, each slot providing a latching shoulder 35 for cooperation with the corresponding bayonet lug 26 to hold the body 25 in the recess.

FIG. 2 shows terminal portions 22a of the printed circuit conductors 22, the terminal portions lying on opposite sides of the recess R. FIG. 2 also shows how the panel may be recessed adjacent the recess R to seat the terminal portions 22a. In this instance the recess R is countersunk for that purpose, the terminal portions 22a being offset accordingly.

The body 25 in FIG. 3 in which the lamp 30* is imbedded is formed with a relatively rigid radial flange 36 which is dimensioned to occupy the countersunk rim of the recess R in FIG. 2 so that the outer surface of the radial flange of the installed body 25 may be substantially flush with the back face of the panel P. It is not necessary to countersink the recess R, however, since the radial flange 36 is relatively thin and adds very little to the over-all thickness of the panel assembly. As best shown in FIG. 5, the radial flange 36 may be provided by bonding a disk 38 of relatively rigid material to the cylindrical plastic body in which the lamp 30 is imbcdded. In this instance, the disk 38 is made of fiber glass, i.e., glass cloth imbedded in rigid plastic material.

In accord with the invention, the lamp-carrying body 25 with the radial flange 36' incorporates conductor means that is at least partially imbcdded in the plastic material of the body to connect the lamp 30 to the lamp circuit and at the same time to provide bridges across the recess R for the associated printed circuit conductors 18 and 22. The conducting means that is incorporated in the flange body 25 for this purpose may be of the construction shown in FIG. 6.

As indicated in FIG. 6, a diametrical conductor means 40 and a pair of shorter radial conductor means 42 are formed on the inner face of the non-conducting fiber glass disk 33 by a printed circuit technique. The two radial conductor means 42 are perpendicular to the diametrical conductor means 46 and are spaced therefrom. The disk 38 with the described conductor means thereon is then provided with suitable apertures such as four small apertures 44 which serve as escape vents for the release of air in the subsequent operation of molding the lampcarrying body 25 to the disk.

A small square 45 of suitable non-conducting material is then bonded to the center of the diametrical conductor means 4t: and a bridging conductor 46 of thin metal, for example copper, is bonded to the two radial conductor means 42 in. the position shown in FIG. 5, the bridging conductor being electrically isolated from the underlying diametrical conductor means 40 by the square 45 of non-conducting material. As indicated in FIG. 5, the bridging conductor 46 may be spot-welded to the radial conductor means 42 as indicated at 48. As may be seen in FIGS. 5 and 6, the bridging conductor '46 has a pair of offsets 53 which form a cradle for the lamp 3t) and is further formed with a pair of angled tongues 52 at its opposite ends.

The next step is to bond a pair of radial conductors 54 to the opposite ends of the diametrical conductor means id, preferably by spot-welding. Each of the radial conto cradle the lamp 30 and is formed with an angled tongue 56 at its outer end.

The lamp 30 which has a pair of wire terminals 58 is mounted on the disk and is cradled by the previously mentioned ofisets 50 and also by the twopairs of tongues 55. One of the wire terminals 58 of the lamp is electrically connected to one of the radial conductors 54 and the other wire terminal is electrically connected to the bridging conductor 46. With the lamp 30 cradled in this manner on the conductor assembly of the disk 38, the cylindrical body 25 of plastic material is molded to the disk around the lamp. The four small apertures 44 prevent trapping of air in this molding operation.

The body 25 that is constructed in this manner is mounted in the corresponding recess R by inserting the body with the bayonet lugs 26 oriented to follow the bayonet slots 28 and then the body is rotated slightly to bring the bayonet lugs into engagement with the latching shoulders 35 of the slot.

At this final mounted rotary position of the lampcarrying body 25, the angled tongues 52 of the bridging conductor 46 register with the adjacent terminal portions of the conductors of one leg of the described printed circuit and the angled tongues 56 of the radial conductors 54 register with the terminal portions of the conductors of the other leg of the lamp circuit. Thus the angled tongues 52 may register with the terminal portions 22a (FIG. 2) of the conductors 22 and the angled tongues 56, of the radial conductors 54 may register with similar terminal portions of the printed circuit conductors 18.

It is to be noted that when the body 25 is mounted in a recess R, the radial flange 36 of the body presses snugly against the panel to flex and flatten the angled tongues 52 and 56. Thus with the angled tongues made of flexible material, the angled tongues exert constant pressure against the associated terminal portions of the printed circuit conductors when the lamp-carrying body is firmly seated in the manner described. A further advantage of the arrangement is that the various flexible angled tongues 52 and 56 serve as spring means for preloading the mounted lampcarrying body 25 to resist any tendency for vibration to unseat the body.

'FIGS. 7 and 8 show a lamp-carrying body 25a with a radial flange 36a which is of the same construction as the previously described lamp-carrying body 25 with the radial flange 36. The lamp body 25a functions as a connector for plugging the printed circuit of a panel into an EMF. source. For this purpose, a male connector element in the form of a cylindrical skirt 60 and a second male connector element in the form of a central axial prong 62 are mounted on the outer face of the fiber glass disk 38a that forms the flange 36a. The cylindrical skirt 60 is connected to at least one of the two radial conductor means 42 and the axial prong 62 is connected to the diametrical conductor means 40. Thus the fitting shown in FIGS. 7 and 8 not only serves as means for mounting a lamp in the panel P but also serves as means to plug the printed circuit of the panel into an source. The lamp 3% may be omitted from the fitting shown in FIGS. 7 and 8 if a lamp is not needed at the location of the fitting. The previously mentioned fittings F in the panel in FIG. 1 are of the character shown in FIGS. 7 and 8 with the lamp 30 omitted.

It is apparent that each of the bodies 25 that is mounted in each of the recesses R in the panel shown in FIG. 1 serves to bridge the conductors that terminate at the rims of the recesses. Thus the lamp-carrying bodies incorporating the bridging conductors make it possible for the legs of the lamp circuit to cross each of the recesses R. This arrangement solves the problem of printing a circuit on the back of a panel with only relatively short conductors from the various lamps to the fittings that plug the panel into an source. All of the lamps mounted in the recesses R in the panel of FIG. I burn brightly because no appreciable voltage drop occurs.

FIGS. 9 and 10 show how the principles of the invention may be applied to the provision of an indicator lamp in the described edge-lighted panel. In this instance, the purpose of the indicator lamp is to inform the pilot when a bay of the aircraft is open. The outer opaque layer 12 of the panel has cut-outs forming indicia 70 to indicate the purpose of the lamp.

A circular opening 72 of the panel P is occupied by an insert, generally designated 74, which is made of light-transmitting plastic material and is permanently bonded in the opening 72 to constitute a unitary part of the panel. The insert 74 is of the configuration of an inverted cup and forms a recess R4 to receive a lampcarrying body 25 which is of the previously described construction shown in FIGS. 3 and 4. The insert 74 is formed with the usual pair of bayonet grooves 75 for cooperation with the previously mentioned bayonet lugs 26 of the lamp-carrying body 25.

The insert 74 is shown in FIG. 10 as protruding forward and the protruding portion is shown as encircled by a circumferential layer 76 of opaque material to prevent lateral transmission of light. The forward transverse wall 7 8 of the recess is made entirely of light-transmitting plastic to permit the light from the lamp 30 to be emitted forwardly from the panel for observation by the pilot. In many instances, it is desirable to have the indicator lamp transmit light of some distinct color, for example, red, blue or green. For this purpose, the transverse wall 78 of the insert 74 may be colored transparent plastic or colored translucent plastic or, if desired, the insert 74 may be made entirely of transparent plastic and the plastic body 25 that encloses the lamp 30 may be of colored transparent plastic or colored translucent plastic.

FIG. 11 shows how a lamp-receiving recess in a panel P may comprise a circular opening R-2 that extends all the way through the panel. In the construction shown, the recess R-2 is provided with a liner in the form of a cylindrical insert 80 of light-transmitting plastic material. The cylindrical insert 80 is provided with the usual pair of diametrically opposite bayonet grooves 82 to cooperate with the usual bayonet lugs 26 of a lamp-carrying body 25a of plastic material. The body 25a imbeds the usual lamp 30 and difiers from the previously described lamp-carrying plastic body 25 only in being of greater axial dimension to occupy fully the recess R-2.

Since the recess R-2 is open all the way to the front of the panel P, it permits light from the lamp 30 to be emitted forward from the panel. The material of the lamp-imbedding body 25a may be colored to cause emission of correspondingly colored light.

My description in specific detail of the selected embodiment of the invention will suggest various changes, substitutions and other departures from my disclosure within the spirit and scope of the appended claims.

I claim:

1. In an edge-lighted panel assembly, the combination of z a panel having a main relatively thick light-transmitting layer, said panel having at least one recess extending into said main layer from one face of the panel; a body of light-transmitting material releasably mounted in said recess; a lamp mounted in said body; a first pair of conductors carried by the panel on one side of an electric circuit terminating at spaced points adjacent said recess; a second pair of conductors carried by the panel on the other side of the circuit terminating at spaced points adjacent said recess; a first conductor means connected to one terminal of said lamp and carried by said body to contact said first pair of conductors to interconnect said first pair of conductors independently of the lamp; and a second conductor means connected to the other terminal of the lamp and carried by said body to contact said second pair of conductors to interconnect the second pair of conductors independently of the lamp.

2. Means for mounting in a back recess in an edgelighted panel adjacent circuit conductors on. the panel for illumination of the panel comprising: a disk of nonconducting material of larger cross dimension than said recess to cover the recess and overlap the rim thereof; a lamp mounted on said disk; 2. pair of conductor means mounted on said disk and insulated from each other,

said conductor means being connected respectively to the opposite sides of the lamp, each of said conductor means being exposed near the margin of the disk on the underside of the disk in contact with said circuit conductors on the panel for energizing the lamp; a body of light-transmitting material shaped and dimensioned to fit into said recess, said body being bonded to said disk and enveloping and carrying said lamp and adjacent portions of said pair of conductor means; and means retaining said body in said recess.

3. A combination as set forth in claim 1 in which said body'serve's as an electrical fitting for connecting said two series of conductors to an E.M.F. source and has two. connector elements extending therefrom, said connector elements being connected to said first and second conductor means respectively for plugging the panel into an source.

4. A combination as set forth in claim 3 in which said body is reieasably mounted in the recess by bayonet connecting means requiring rotation of the body relativeto the panel; and in which said connector elements are concentric elements positioned coaxially of the axis of rotation of the body.

5. In an edge-lighted panel assembly, the combination of: a panel having a main relatively thick light-transmitting layer, said panel having at least one recess extending into said main layer from one face of the panel; a body of non-conducting material mounted in said recess; afirst pair of conductors carried by said panel on one side of an electric circuit terminating at two circuit terminating at two other spaced points adjacent said recess; a first conductor means and a second conductor means carried by said body in contact with said first and second pairs of conductors respectively; and two connector elements carried by said body and projecting therefrom for plugging the panel into an source, said two connector elements being connected to said first and second conductor means respectively.

6. A combination as set forth in claim 2 in which said recess is a bore and the bore is countersunk to form a seat around the rim of the bore for said disk.

References Cited in the file of this patent UNITED STATES PATENTS 2,171,431 Kollsman Aug. 29, 1939 2,637,802 Roper et a1. May 5, 1953 2,688,688 Holtz Sept. 7, 1954 2,702,340 Thieblot Feb. 15, 1955 2,791,050 Neugass May 7, 1957 2,795,069 Hardesty June 11, 1957 2,824,954 Roper Feb. 25, 1958 2,838,865 Hardesty June 17, 1958 2,847,560 Peak et a1 Aug. 12, 1958 2,853,595 Baldwin Sept. 23, 1958 2,855,710 Roper Oct. 14, 1958 2,880,536 Sullivan Apr. 7, 1959 2,923,860 Miller -1 Feb. 2,1960 2,945,313 Hardesty July 19, 1960 2,948,073 Roper Aug. 9, 1960 2,959,880 Detloflr Nov. 15, 1960 2,987,695 Peak et a1 June 6, 1961 

1. IN AN EDGE-LIGHTED PANEL ASSEMBLY, THE COMBINATION OF: A PANEL HAVING A MAIN RELATIVELY THICK LIGHT-TRANSMITTING LAYER, SAID PANEL HAVING AT LEAST ONE RECESS EXTENDING INTO SAID MAIN LAYER FROM ONE FACE OF THE PANEL; A BODY OF LIGHT-TRANSMITTING MATERIAL RELEASABLY MOUNTED IN SAID RECESS; A LAMP MOUNTED IN SAID BODY; A FIRST PAIR OF CONDUCTORS CARRIED BY THE PANEL ON ONE SIDE OF AN ELECTRIC CIRCUIT TERMINATING AT SPACED POINTS ADJACENT SAID RECESS; A SECOND PAIR OF CONDUCTORS CARRIED BY THE PANEL ON THE OTHER SIDE OF THE CIRCUIT TERMINATING AT SPACED POINTS ADJACENT SAID RECESS; A FIRST CONDUCTOR MEANS CONNECTED TO ONE TERMINAL OF SAID LAMP AND CARRIED BY SAID BODY TO CONTACT SAID FIRST PAIR OF CONDUCTORS TO INTERCONNECT SAID FIRST PAIR OF CONDUCTORS INDEPENDENTLY OF THE LAMP; AND A SECOND CONDUCTOR MEANS CONNECTED TO THE OTHER TERMINAL OF THE LAMP AND CARRIED BY SAID BODY TO CONTACT SAID SECOND PAIR OF CONDUCTORS TO INTERCONNECT THE SECOND PAIR OF CONDUCTORS INDEPENDENTLY OF THE LAMP. 